docs: def _get_input_steps(self):
          """
          Search and return all steps that have no parents. These are the steps that are get the input data.
          """
          input_steps = []
  
          for step in self.steps_sorted:
              parent_steps = self._parent_steps(step)
  
              if len(parent_steps) == 0:
                  input_steps.append(step)
  
          return input_steps